This invention relates generally to hypodermic needles and syringes, and more particularly the invention relates to a disposable syringe and safety needle assembly.
The safe use and disposal of hypodermic needles and syringes are a concern in the medical and health professions. Needle stick injuries following use of a needle pose a risk to both patient and user, and especially with present risk of HIV and HBV infection care must be taken in the safe handling and disposal of used needles and syringes. A safety cover for the used needle is a recognized requirement.
A number of safety syringe designs incorporating needle covers have been proposed. U.S. Pat. No. 4,909,791 and No. 4,982,842 employ jaw members pivotally mounted on a syringe barrel for covering a needle after use.
U.S. Pat. No. 4,883,471 and No. 4,935,014 disclose syringe assemblies in which the needle is drawn into the syringe after use.
U.S. Pat. No. 4,969,877 discloses a syringe assembly in which an outer casing is provided around an inner chamber or syringe portion which slides in the outer casing to an operational position and to a retracted position at the forward and rearward ends of the outer casing, respectively.
U.S. Pat. No. 4,874,382 incorporates a protective shield within the body of a syringe into which a needle is drawn after use. A spring biasing mechanism is required in drawing the needle into the sheath.
U.S. Pat. No. 4,863,435 incorporates an outer shield which is spring biased to slide on the syringe to cover a needle after use and which is retractable on the syringe to permit needle injections.
While each of these safety syringes provides some protection against accidental needle injury, the designs require a relatively complex mechanism, are bulky in handling and use, and expensive to manufacture. Moreover, actuation of the safety features can require use of both hands of the user.
The present invention is directed to an improved safety needle and syringe assembly which overcomes limitations of the prior art.